1. Field
The present disclosure relates generally to telecommunication systems, and more particularly, to time slicing concepts for variable data rate encoding.
2. Background
Digital video and audio compression technologies have ushered in an era of explosive growth in digital multimedia application. Since the early 1990's, international standards groups such as, for example, the Video Coding Experts Group (VCEG) of ITU-T and the Motion Pictures Expert Group of ISO/IEC, have developed international video recording standards. The standards developed include, for example, MPEG-1, MPEG-2, MPEG-4 (collectively referred to as MPEG-x), H.261, H.262, H.263, and AVC/H.264 (collectively referred to as H.26x).
The MPEG-x and H.26x standards describe data processing and manipulation techniques that are well suited for the compression and delivery of video, audio and other information. In particular, the above-referenced standards, and other hybrid coding standards and techniques compress video information using intra-frame coding techniques (such as, for example, run-length coding, Huffman coding and the like) and inter-frame coding techniques (such as, for example, forward and backward predictive coding, motion compensation and the like).
Inter-frame coding exploits the fact that there are very few differences between two adjacent frames in a video sequence. Often the only difference is that some parts of the image have shifted slightly between frames. Inter-frame prediction coding can be used to partition a current frame into a macroblocks (i.e., a group of pixels) and search an adjacent frame, or reference frame, to determine whether the macroblock has moved. If the content of the macroblock in the current frame can be located in a reference frame, then it does not need to be reproduced. The content can be represented by a “motion vector” indicating its displacement in the current frame from its position in the reference frame and the difference between the two macroblocks. Intra-frame prediction coding, on the other hand, is performed without reference to an any frame, and therefore, requires significantly more bandwidth than a frame with inter-picture prediction coding. Intra-picture frame is generally used to launch a new scene in a video sequence.
These standards and coding techniques are widely deployed today in digital multimedia applications for wireless networks. In these applications, compressed data from various content providers may be distributed to a large number of access terminals using a technique know as time slicing. “Time slicing” is the time-division multiplexing of services from various content providers. In other words, the data of one particular service is not broadcast continuously, but rather in periodic bursts. This approach tends to conserve power at the access terminal because only the parts of the data stream which carry the data of the service currently selected by the viewer have to be processed. However, the amount of data contained in a burst must be sufficient to support continuous playback on the viewer device until the next burst of data is received.